19 
truly, as Mr. Sydney Webb remarks, “ it is curious how history repeats 
itself.” 
As one of my principal objects in preparing this paper is to bring 
before your notice and that of entomologists generally, the absolutely 
certain fact of the distinctness of the two, and the equally certain fact of 
the existence of red forms of unidentaria, Haw., and thus to leave no 
possible excuse for going over the same ground again in the future 
history of entomology, my first point must be to demonstrate their 
structural distinctness, after which I shall group my other remarks under 
the following heads—Synonymy, Differentiation by Wing-markings, 
Variation, Geographical Distribution, Habits, Early Stages. 
Structural chahacteristics. —With regard to structural distinct¬ 
ness, my article in the Record, referred to above, called forth a response 
from that careful and accurate observer, Mr. E. N. Pierce, to the effect 
that the male genitalia differed more widely even than might have been 
expected in two such close allies, and in the Record, vol. iii., p. 177, he 
gave rough figures of the forms of the “harpes,” in each of the two, 
though unfortunately the names were reversed in the appended note. 
If members possessing copies have not yet corrected them, may I suggest 
that they should do so to avoid confusion. As an artificial aid to memory 
for those who desire to recollect which form of structure belongs to 
which species, I would point out that the species we are accustomed to 
call “ unidentaria ,” is that in which the harpes are strongly dentated. 
Thanks to the great kindness of Mr. Pierce, who stands prominent 
among the many entomologists who have rendered me willing assist¬ 
ance, a number of specimens have been investigated from this point of 
view, and he has further obligingly sent me his preparations for study 
and for exhibition this evening, so that I hope to be able to convince 
the most sceptical of the invariability of the form of the genitalia, and 
the consequent confirmation of the view arrived at by breeding and by 
superficial comparisons. 
The course which we folloAved was this:—First, I detached the 
abdomina of ten of my most disputable specimens (recognizable in my 
cases this evening by the absence of those parts, and by the reference 
numbers attached), and sent them to Mr. Pierce in separate boxes, with 
numbers corresponding to those which I at the same time pinned on to 
the specimens, but without giving him any clue as to the identity of the 
specimens. He then mounted the portions on which he relies for the 
differentiation, and wrote me that “ Nos. 2, 4, 5, 7, 8, are typical uni¬ 
dentaria (as we know it) ” and so on. I will quote a short portion of 
his letter :—“ In making so many preparations, I am much struck with 
the uniformity of size of the whole apparatus; the length in ferrugata 
is in each instance about one-third larger than in unidentaria, and this 
appears quite constant in what I have examined.In the 14 
unidentaria and 10 ferrugata that I have mounted, I find no trace of the 
one at all approaching the other; the tooth-like projections which are 
always strongly present in unidentaria, are always quite absent in ferru¬ 
gata ; this is, of course, in addition to the parts being differently shaped, 
in fact, they are as easy to separate as the antennas of male and female 
Bombyx quercus .” I was gratified to find from Mr. Pierce’s determina¬ 
tion that I had correctly named every specimen, though, as will be seen, 
some are worn captured specimens, and I had not felt very great 
confidence in myself in one or two cases. I then sent the specimens 
